The effects of clear-cutting and liming on the soil macrofauna of a beech forest

Management Forest Ecology and Management 77 (1995) 35-51

The effects of clear-cutting and liming on the soil macrofauna of a beech forest Anne Theenhaus * , Matthias Schaefer II. Zoologisches

Instinct, Abteilung

Ckologie,

Universitiit

GBttingen,

Berliner

Strasse 28, D-37073

Giittingen,

Germany

Accepted 1 May 1995

Abstract The effect of clear-cutting and liming on abundance, dominance structure and trophic composition of the soil macrofauna (Lumbricidae, Diptera, Coleoptera and Chilopoda) was studied in a beech wood forest on an acidic brown-earth. Sampling methods were ground photo-ecledors and funnel extraction. The various taxa and nutritional groups of Diptera responded differently to the environmental changes caused by clear-cutting and liming. The same was true for the species and taxa of Coleoptera. Lumbricidae and Chilopoda were favoured by the liming treatment. The factors determining the change in population densities are discussed. Abiotic factors, especially soil moisture, and biotic factors, such as dead plant biomass and predation, are considered to be of prime importance. A change of moder soil into mull soil after liming is observed. Keywords:

Clear-cutting; Liming; Beech forest; Macrofauna

1. Introduction Clear-cutting as a restocking method is common practice in today’s forestry management. In addition, the liming of forests is a common strategy for mitigating the problem of acid rain. However, the environmental effects of these treatment strategies and the interaction between them are not well understood. It is quite reasonable to assume that abrupt changes in an ecosystem, such as clear-cutting and liming, would be mirrored in the composition of the animal community. The objective of this study is to determine the changes in population density, dominance structure and trophic composition of the soil

* Corresponding author.

macrofauna from the initial state of a succession after clear-cutting, with and without liming. According to Odum (19711, in the early stage of ecological succession community respiration is low compared to mature ecosystems. Schaefer (1991a) points out that decomposition is less than net production during the development of a forest. The number of decomposers is consequently lower than in mature stands. In this study it is, therefore, hypothesized, that the decomposer community declines after clearcutting. Furthermore, we assume that the saprophagous macrofauna is more abundant on the limed plots and causes a change of moder into mull profile. Schauermann (1986) states that, in general, saprophages are more abundant in mull soils than in moder soils. According to Schaefer (1991b), decomposition rates are generally higher in mull than in moder or mor

037%1127/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved 0378-1127(95)03580-X

SSDI

A. Theenhaus,

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forest soils, contributing to a lower standing crop of soil organic matter in the first soil humus form. In mull soils, the higher decay rates are the result of litter comminution by the macrofauna, mixing of organic material with the mineral soil and the maintenance of well-drained aerobic conditions in the soil. Moder soil, on the other hand, has low pH values in all strata, which inhibit the macrofauna and prevent its feeding and burrowing activities (Swift et al., 1979).

2. Materials

and methods

2.1. Site

The Soiling is a plateau of triassic red sandstone (Buntsandstein) about 50 km north-west of Gottingen (Lower Saxony). It is overlain with a layer of loess loam that is more than 50 cm thick. The soil is composed of an acidic brown-earth with a pH value (KC0 lower than 4.2. The humus form is a typical moder. Since the process of litter decomposition is rather slow, the litter-humus layer is up to 5 cm thick. The experiment was performed in the upper Solling (‘Hochsolling’), 500 m above sea level. At this altitude, the climate is suboceanic-montane (Ellenberg et al., 1986). Average annual rainfall is 1045 mm, average annual temperature 6.5”C. The site under investigation, previously designated as B2 plot, is a beech forest of the LuzuloFagetum typicum type. Most of the trees, predominantly Fagus syluatica L., are about 150 years old. The ground flora consists of Luzula luzuloides (Lam.), Oxalis acetosella L., Deschampsia flexuosa L. and seedlings of Fagus sylvatica L. The ground flora is extremely sparse, and a shrub layer is not present. A detailed description of the study site is given in Ellenberg (1971). 2.2. Experimental

T I 0 .I

30m

clear-cut

I

limed

70m

I

area

area

/’

0

Ir

zoological plots (1Om x 5m)

Fig. 1. Experimental site (B2 area) in the beech forest of the upper Solling (Lower Saxony).

of3tha-‘. Eight plots, each measuring 10 m X 5 m, were reserved for zoological research. Four of them were located within the clear-cuts, two of which were limed. The other two plots in the clear-cut areas remained unlimed. Each of the other four plots were located south of a clear-cut area within the beech forest. Two of the plots were located within the limed areas, the other two in the unlimed areas (Fig. I).

design 2.3. General properties of the tqwrimental plots

In October 1989, four clear-cuts, measuring 30 m in diameter, were created at least 50 m apart. A total of 64 beech trees were cut and removed from the experimental site. Two of the clear-cuts, including a surrounding forest area 20 m wide, were limed with fine-grained magnesium carbonate in a concentration

2.3.1. Vegetation and litter fall

The limed plots had a dense herb layer. In June 1992 it covered 70-100% of the forest floor. The dominating species was Epilobium angustifolium CL.), followed by Luzula Zuzuloides(I&RI.) and Ox-

A. Theenhaus, Table 1 pH and element

concentrations

Horizon

pH (CaCl,)

Unlimed

horizons

Forest Ecology

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77 (1995)

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O,, Or and 0, in the beech forest stand, the unlimed

37

and the limed

clear-cut

P

K

Ca

k,

iz8

(mg g-l)

(mg g-l)

(mg g-l)

Mg (mg g-l)

3.42 b 2.81 b 2.72 b

43.3 34.1 ab 31.3

1.72 1.93 ab 1.71

0.94 0.95 1.15 a

1.83 1.37 b 3.65

3.92 b 2.31 b 1.07 b

1.11 0.97 b 1.86 ab

4.79 a 4.11 a 3.38 a

41.5 34.2 b 30.6

1.58 1.60 b 1.62

0.98 0.84 0.69 b

2.24 2.91 a 3.16

7.08 a 12.16 a 3.39 a

2.18 4.89 a 3.89 a

43.7 43.7 a 32.1

1.77 1.99 a 1.70

1.05 0.85 0.98 ab

2.01 1.40 b 4.12

plots

clear-cut

0, Of Oh

Limed clear-cut 0, 0‘ Oh

Beech forest stand 3.83 ah 0, Of 2.88 ab Oh 2.69 b Figures

of the organic

M. Schaefer/

sharing

the same letter are not significantly

different

(Wilcoxon-test

alis acetoselh L. By contrast, the unlimed plots were sparsely covered with herbs (2-20%). Leaf litterfall into the clear-cuts from the surrounding beech trees amounted to 75% of the litterfall in the beech forest (2.9 t ha-‘). Total litter input in limed clear-cuts increased, because on these plots an additional 2.8 t ha-’ of organic dry matter was supplied by the above ground herbaceous vegetation (Bauhus and Bartsch, 1995). 2.3.2. Precipitation,

4.86 ab 2.81 ab 1.15 b

at P < 0.05) (Bauhus,

0.75 0.58 b 1.20 b

1994).

2.3.3. pH and element fluxes

pH, element concentrations and element exchange capacity are presented in Tables 1 and 2. In the beech forest stand negligible amounts of nitrate were measured in the seepage water at 80 cm depth (Bauhus and Bartsch, 1995). Here sulphate and aluminium were the dominant ions in the seepage water. In the clear-cut plots disruption of plant uptake and high infiltration rates in the unlimed clear-

soil moisture and temperature

Due to the lack of tree cover, in each of the clear-cuts, more precipitation reached the ground. In 1991 and 1992, Bauhus and Bartsch (1995) reported 7% more precipitation reaching the ground in the clear-cuts than in the beech forest. Soil water tension differed enormously between the clear-cut plots and the beech forest plots. In the clear-cut plots, the water tension at a depth of 15 cm was close to saturation point throughout the year. By contrast, in the beech forest the soil dries during late summer (830 hPa), because of water removal by the beech trees (Bauhus and Bartsch, 1995). Average daily soil temperatures in the clear-cuts were not different from those in the beech forest stand on average. However, maximum daily temperatures were on some occasions warmer in the stand than in the clear-cuts (Bauhus and Bartsch, 1995). This was most obvious during the summer when maximum temperatures at 5 cm depth were sometimes 4°C higher than in the beech forest stand.

Table 2 pH and cation exchange capacity of the surface mineral beech forest stand, the unlimed and the limed clear-cut Depth (cm)

pH (CaCl,)

C (%I

N (o/o)

K (pm01

Unlimed o-1 l-2 2-5 S-10

clear-cut 2.76 ab 2.83 ab 2.94 ab 3.17 ab

11.3 6.1 4.4 3.4

0.6 0.3 0.2 0.2

3.4 2.9 ab 2.2 b 1.8 b

6.8 4.7 2.8 2.2

b b b a

2.9 2.1 1.3 1.1

77.2 82.9 88.1 98.5

10.9 7.1 4.3 3.0

0.6 0.4 0.2 0.2

2.9 2.0 a 1.5 a 1.2 a

36.1 14.6 8.3 3.2

a a a a

15.3 6.5 3.4 2.8

52.7 72.0 82.7 87.7

12.0 6.5 4.3 3.1

0.6 0.3 0.2 0.2

4.3 2.9 b 2.0 ab 1.4 a

4.0 2.8 1.8 1.2

b b b b

2.5 1.8 1.2 1.0

73.4 83.3 93.7 96.9

Limed clear-cut o-1 3.19 = l-2 3.03 = 2-5 3.07 a S-10 3.30 a Beech forest stand o-1 2.71 b l-2 2.78 b 2-5 2.89 b S-10 3.15 b

Ca IE g-l)

Mg

soil in the plots

Figures sharing the same letter are not significantly (Wilcoxon-test at P < 0.05) (Bauhus, 1994).

AL

different

38

A. Theenhaus,

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Ecology

cut plots caused substantial nitrate losses: 80 kg NO;-N ha-’ aa1 were lost from the unlimed clearcut plots and 30 kg NO,-N ha- ’ a-r from the limed clear-cut plots (1992) (Bauhus, 1994). This process caused soil acidification and aluminium release. Therefore, nitrate and aluminium were the dominant ions in the seepage water of clear-cuts. In the limed clear-cut plots (1991), less nitrogen was mineralized, compared to the unlimed clear-cut plots (Bauhus and Barthel, 1994). 2.4. Sampling of the fauna On 11 March 1992, a total of 24 ground photoeclectors (three on each zoological plot) (Funke, 1971), each covering 0.3 m2 were randomly set up. Sampling was done every 2 weeks. The last day of sampling was 4 November 1992. Nine soil cores (diam. l/28 m2, 10 cm depth) per plot, including the litter layer, were taken four times during that year: in spring (27 May 1992), in summer (5 August 1992), in autumn (11 November 1992) and in winter (3 February 1993). The samples were extracted using an apparatus designed by Kempson et al. (1963), modified by Schauermann (1982). 2.5. Statistical treatment The influence of liming and clear-cutting on the soil macrofauna and the interaction between these factors were tested by two-way analysis of variance (ANOVA). A block design was set up, each adjacent forest plot and clear-cut plot representing one block. Factors were liming and clear-cutting. Variance homogeneity was tested using the Bartlett test. For many groups of soil fauna, caught by the funnel extraction method, the analysis of variances was not applied, because there was no variance homogeneity. In these cases only tendencies are described.

3. Results

and discussion

During the experiment, a total of 1600 specimens of Lumbricidae, 18 800 of Diptera, 2800 of

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77 (199.5) 35-51

Table 3 Population density (ind. m ’ ) of Lumbricidae on the limed (Ii) and unlimed (unli) clear-cut and the limed (ti) and unlimed funli) beech forest plots in the Solling mountains (1992/1993) ____-. _Clear-cut Forest

Dendrobaena octaedra 6av.i Dendrodrilus rubidus (Sav.) Dendrobaena / Dendrodrilus, Lumbricus eiseni (Lev.) Lumbricus rubellus Hoffm. Lumbricus, juvenile

juvenile

li

unli

19 20 250 9 2 8

3 1 7 0 (1 +

Funnel extraction method (mean of four sampling between 0 and 1 ind. m-l found.

Ii -- -~.16 20 264 ! 1 3

unli i 0 h 0 !i ii

dates 1992). ;

Coleoptera, 500 of Lithobiomorpha, 70 of tipulid larvae and 2400 larvae of Athous subfuscus were identified. Other macrofauna groups were represented only with low numbers and were therefore not included in the study: 12 Gastropoda, 14 Diplopoda, about 100 Hymenoptera and 15 Lepidoptera. 3.1. Lumbricidae Liming led to an increase of the abundance of all lumbricid species (Fig. &a) and Table 3). On the unlimed plots the average density of Lumbricidae was 10 individuals (ind.) m-‘, whereas a very high number, an average density of 307 ind. m-‘, was found on the four limed plots. A positive correlation between the density of Lumbricidae and the lime content of the soil has been found by many authors (e.g. Piearce, 1972; Hnhta, 1979; Schauermann, 1986; Funke, 1991). Presumably the comparatively high pH value (Table 1 and 2) of the soil on the limed plots caused the increase in Lumbricidae. Another favouring factor on the limed plots presumably was the high herbaceous biomass, especially decaying material of Epilobium angustifolium. Clear-cutting had no obvious influence on the density of Lumbricidae on both unlimed and limed plots. Huhta (1976) found an increase in Lumbricidae during the first few years after clear-cutting. The author attributed this finding to the higher amount of organic matter remaining in the soil in the form of felling residues. In the present study, however, trees were removed from the clear-cuts and, furthermore, the concentration and cation exchange capacity of

A. Theenhaus,

M. Schaefer/Forest

Ecology

nutrients, such as N and P, did not significantly increase in the clear-cuts (Tables 1 and 2). The occurrence of Lumbric~ eiseni (Lev.) is worth mentioning. This species is very rare in Germany. Lumbricus eiseni was found only on the limed plots (both forest plots and clear-cut plots). We cannot imagine how this population has colonized these plots.

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77 (1995)

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39

emergence abundance value of 4114 Diptera rnm2. Of these 3.3% were Brachycera. Sciaridae were predominant, comprising 77.9% (3205 ind. me21 of the total catch, followed by Sciophilidae with a percentage of 9.5% of the total catch (390 ind. ms2>. Cecidomyiidae (including Lestremiinae) comprised 7.1% (292 ind. mp2) of the total catch of Diptera. Hovemeyer (1991) pointed out that, in acidic beech woods, Sciaridae are usually more abundant than Cecidomyiinae. The high emergence abundance of Chironimidae on the unlimed clear-cut plots, found in this study, could possibly be attributed to the fact that the emergence abundance of Diptera is subject to fluctuations from year to year (e.g. Altmtiller, 1979). Despite the fact that the dominance structure of the dipterous community varied greatly between the experimental plots, no pattern became evident. Chironomidae were an exception, since the dominance position of Chironomidae on the two unlimed beech forest plots was relatively high. However, it is not an increase of Chironomidae, but rather the reduced emergence abundance values of Cecidomyiinae, on these plots that could be the explanation for this finding. In Table 5, only those Diptera taxa are listed where the statistical test revealed significant differences in the emergence abundance between the treat-

3.2. Diptera Species belonging to 33 families of Diptera were found. Of these, 14 belonged to Nematocera and 19 to Brachycera. The average emergence abundance of Diptera was 2600 ind. m- 2. The lowest density (1027 ind. mm21 was recorded on an unlimed clear-cut plot. The highest density (5051 ind. rnp2) was recorded on a limed clear-cut plot. Of the total catch 7% were Brachycera. The most abundant taxa were Cecidomyiinae (28.7-64.3% of the total catch), Sciaridae (20.133.8%) and Chironomidae (1.9-17.5%) (Table 4). On all but one plot, Cecidomyiinae were predominant, followed by Sciaridae. On the unlimed clear-cut plots, Chironomidae were relatively dominant comprising 17.5% of the total catch. On an area of beech forest adjacent to the site examined in this study, Altmiiller (1976) found an

Table 4 Cumulative emergence abundance of Diptera (ind. m -‘) and percentage of taxa of the total catch of the respective plot (%, mean values of two plots) on the limed and unlimed clear-cut and beech forest plots in the Solling mountains (1992/1993) (catches of ground uhoto-eclectors) 1

Cumulative

emergence

Clear-cuts

Cecidomyiinae Sciaridae Chironomidae Sciophilidae Phoridae Ceratopogonidae Lestremiinae Empididae Fanniidae Hybotidae Dolichopodidae Scatopsidae Only taxa which

comprised

abundance

(ind. m-’

)

Forest

Percentage

of taxa

Clear-cuts

Forest

li

unli

li

unli

li

unli

li

unli

2373 742 69 73 118 104 34 9 31 22 29 13

414 467 253 62 57 64 14 32 14 19 24 0

1477 970 102 77 58 11 38 16 31 14 14 34

1477 589 49 85 47 10 39 44 14 23 6 5

64.3 20.1 1.9 2.0 3.2 2.8 + + + + + +

28.7 32.4 17:s 4.3 3.9 4.4 1.0 2.2 1.0 1.3 1.7 +

51.4 33.8 3.5 2.7 2.0 + 1.3 + 1.1 + + 1.2

60.8 24.2 2.0 3.5 1.9 + 1.6 1.8 + + + +

at least 1% of the total catch on at least one plot are presented.

+, numbers

< 1%.

A. Theenhaus,

40

M. Schaefer/Forest

Table 5 Taxa of Diptera whose emergence abundance influenced by the factors of clear-cutting and/or

was significantly liming (ANOVA)

Taxon

Factor

Effect

Significance

Cecidomyiinae Total First peak Second peak Ceratopogonidae Dolichopodidae Empididae Fanniidae Limoniidae Limoniidae Lonchopteridae Scatopsidae Sciaridae

Liming X clear-cutting Clear-cutting Liming Xclear-cutting Clear-cutting Clear-cutting Liming Liming Clear-cutting Liming Liming Xclear-cutting Liming Liming

+ -

r f L* *

+ + + -

- * * .I* ,.

X , interaction the emergence

I * * t .I *.*

+ + + + + +

* * * . * * 4*

of the factors; + / - , positive/negative effect on abundance. * * *P < 0.001, * * P < 0.01, ’ P <

0.05.

ments. The emergence abundance value of total Diptera was significantly higher on the two limed clear-cut plots, compared to the other plots (P <

Ecology

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77 (1995)

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0.01) (Fig. 2(a)). The same result was obtained for Cecidomyiinae, which made up 50% of Diptera (P < 0.01). During the year under observation, two emergence peaks of Cecidomyiinae were recorded: the first in April, the second between the beginning of June and the end of August (Fig. 2(b)). During the second peak, the highest number of Cecidomyiinae were detected on the limed clear-cut plots (P < 0.001). The April catches were significantly higher on the beech forest plots, in comparison to the clear-cut plots (P < 0.0011. The reduced emergence characteristic for the first peak on the clear-cut plots is difficult to interpret. The larvae of the Cecidomyiinae present are assumed to be gall-making. In autumn the larvae, inside the leaves, fall to the ground and enter the soil for aestivation and/or hibernation. Since all experimental plots had roughly the same amount of litter, the decline in the emergence abundance on the clear-cut plots can not be attributed to a reduced litter biomass. One possible explanation for the decline in Cecidomyiinae on the clear-cut plots could be, that, for some reason, the adult Cecidomyiinae avoid the edges of the clear-cuts for oviposition.

Ind /m; 4oc0,

b) Cecidomyiinae 3000

2000 1000 0L

Ei Nemalocera

0

Brachycera

d) microhumiphagous Diptera

Fig. 2. Emergence abundances and/or activity density of the soil macrofauna (ind. m-‘) on limed and unlimed clear-cut plots, and on limed and uniimed beech forest plots in the Solling mountains, sampled with ground photo-eclectors. Capture period 11 March to 4 November 1992. cl noli, clear-cut, not limed, cl li, clear-cut, limed; fo noli, beech forest, not limed; fo li, beech forest, l&ted.

A. Theenhaus,

M. Schaefer/Forest

3.2.1. Trophic groups of Diptera In order to point out functional aspects, catches of Diptera were subdivided into trophic groups, according to the feeding habitats of their larvae. The articles by Brauns (19541, Raw (19671, Hennig (19681, Healey and Russel-Smith (19711, Jacobs and Renner (1988) and Hovemeyer (1985, 1992) were helpful literature for this categorization. The statistical analysis for mycetophagous feeders (Platypezidae, Mycetophilidae, Sciophilidae and Lestremiinae) revealed no significant differences between the treatments. Okland (1994) compared the species richness of Mycetophilidae between clearcuts, managed forest sites, which were clear-cut 70-120 years ago, and semi-natural forests (only selectively cut). The author found no significant difference between clear-cuts and managed forest sites; however, the average number of species was significantly higher in semi-natural forests. The author concluded that the restoration of a diverse mycetophilid fauna after clear-cutting requires more time than 70-120 years. This view fits to the findings of the present study, since the beech forest under survey is about 150 years old and the mycetophilid fauna might still be in a developing state. The necrophagous feeders (Phoridae, Sarcophagidae, Sphaeroceridae) were not influenced significantly by the treatments clear-cutting and liming. The trophic groups showing differences were macrohumiphages, microhumiphages, ‘surface scrapers’ and zoophages.

3.2.1.1. Macrohumiphages.

Those taxa which feed on litter (microflora and amorphic humus included) are assigned to the macrohumiphagous feeders. These are Limoniidae, Trichoceridae, Tipulidae, Scatopsidae, Sciaridae, Bibionidae and Psychodidae. The emergence abundance of macrohumiphagous feeders significantly increased after liming (P < 0.001) (Fig. 2(c)). This was mainly due to an increase in population density of Sciaridae (P < 0.011, Scatopsidae (P < 0.01) and Limoniidae (P < 0.001) (Table 5). Besides, limoniid numbers were significantly higher on the clear-cut plots relative to the beech forest plots (P < 0.001) (Table 5). With one exception, no Tipulidae hatched on the unlimed plots. The emergence abundance value was 2 ind. mm2 on average on the limed clear-cut plots.

Ecology

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77 (1995)

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41

Similar patterns were observed for the tipulid larvae collected by funnel extraction. The highest number of tipulid larvae were found on the limed plots, ranging from 8 to 13 ind. m-‘. On the four unlimed plots 2-7 ind. me2 were found. The increase in macrohumiphagous feeders on the limed plots could be attributed to the relatively high biomass of herbs (especially Epilobium angustifolium), which served as food resource for the macrohumiphagous feeders. In addition, the relatively high pH value on the limed plots could have favoured the macrohumiphagous feeders, of which Tipulidae are known to avoid acidic habitats. Irmler and Heydemann (1989) found a positive correlation between the pH value of the soil and the average population density of tipulid larvae. According to Funke (19911, however, the emergence abundance of Sciaridae did not change significantly after the application of lime and fertilizer to a spruce forest in Germany. According to many authors, macrohumiphagous larvae thrive on moist substrates. Cramer (1968) observed this preference in the adults and the larvae of Tipulidae and Limoniidae. Funke (1991) found that Limoniidae are most abundant in moist forests. Hovemeyer (1985) reported a decline in emergence abundance of Limoniidae in years following dry summers. The development of sciarid larvae is favoured by a high moisture content of the litter layer and the upper soil layers during summer dryness (Hovemeyer, 1985, 1991). In this study, however, no positive correlation between the moisture content of the habitat and the abundance of macrohumiphagous feeders could be found. Instead, this study revealed an increase in the macrohumiphagous dipteran numbers on the limed plots. On these plots, the moisture content did not show an increase at a depth of 4 cm (the majority of macrohumiphagous dipteran larvae inhabit a depth of about 4 cm; Hovemeyer, 1984).

3.2.1.2. Microhumiphages.

Microhumiphages feed on microfungi, algae, Testacea and amorphic humus. Ceratopogonidae and Chironomidae are assigned to the microhumiphagous feeders. The emergence abundances of all microhumiphagous feeders (Ceratopogonidae and Chironomidae) increased significantly after clear-cutting (P

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< 0.05) (Fig. 2(d)). Statistical proof for this pattern could be given for Ceratopogonidae (P < 0.001; Table 5), but not for Chironomidae. Liming caused an increase in the emergence abundance of all microhumiphagous feeders but a decrease on the beech forest plots. However, the interaction of clear-cutting and liming was not significant (P = 0.098). The significant increase in microhumiphagous feeders due to clear-cutting could be attributed to the moisture content of the habitat, as Ceratopogonidae and Chironomidae prefer moist habitats. The positive influence of moisture on Ceratopogonidae was pointed out by Feldmann (1992). Hovemeyer (1985) reported a positive linear correlation between the density of ceratopogonid larvae and the relative water content of the organic soil layer. Healey and Russel-Smith (1971) and Heynen (1988) described the same preference for Chironomidae. It is not surprising, therefore, that Ceratopogonidae and Chironomidae preferred the clear-cut plots, because here the upper strata of the soil, which are the habitat of

3.2.1.3. ‘Surface scrapers’. The ‘surface scraping’ Diptera feed on microorganisms, pollen and humus material on the leaf surface. The larvae scrape this material off the leaf surfaces with their mandibles. Lonchopteridae, Lauxaniidae and Fanniidae belong to this feeding group. The emergence abundance values of the ‘surface scrapers’ increased after liming (P < 0.001) (Fig. 3(a)). The same is true for Fanniidae (P < O.OOl>, which comprised 65% of the ‘surface scrapers’. Lonchopteridae were significantly more abundant on the limed clear-cut plots compared to all the other plots (Tukey’s least significant difference of P < 0.001). Individuals of this family almost exclusively emerged

ind lmr ICC!

b) zoophagous

Faniwdae

35-51

populations belonging to these families (Hovemeyer, 1984), were relatively moist compared to the beech forest plots. During the summer, the water tension in the beech forest at a depth of 5 cm reached a value of 600 hPa (J. Bauhus, personal communication, 1993).

Ind lm2

q

77 (1995)

0 Lauxanlldae

0 Lonchoptendae

q

Empldidae

Ditm

q

GDollchopod~dae

Hybotldae

mother

lnd /m2

Ind lm2 300,

r7lI

I

100

c) totalCoklptera

200

I

d) Curculionidae

El

102

0 eclector

method

q

funnel

method

q q

Phyllobius

argentatus

h3Str

Poh/drusus

undatus

nother

melanogrammum

Fig. 3. Emergence abundances and/or activity density of the soil macrofauna (ind. m -*) on limed and unlimed clear-cut piots, and on limed and unlimed beech forest plots in the Solling mountains, sampled with ground phot+eclectors. Capture pried 11 Mz&h to 4 November 1992. cl noli, clear-cut, not limed; cl li, clear-cut, limed; fo noli, beech forest, not limed; fo li, beech forest, limed.

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Ecology

from these plots. Emergence abundance values of the Lauxaniidae, however, were comparable for all experimental plots. In summary, every family of the Table 6 Population density (ind. m-*) plots in the Solling mountains

of Coleoptera (1992/1993),

and Management

(unli)

clear-cut

CARABIDAE Noriophilus biguttatus CF.1 Trechus quadristriatus (Schrk.) Bembidion lampros (Hbst.) Trichocellusplacidus (Gyllenhal) Pterostichus oblongopunctatus CF.1 Pterostichus metallicus CF.1 Trichotichnus laeuicollis (Duft.1 HYDROPHILIDAE Megasternum boletophagum

Marsh.

Forest unli

and the limed Funnel

Photo-eclectors

li

43

‘surface scrapers’ responded differently to the environmental changes, caused by clear-cutting and liming.

on the limed (li) and unlimed mean density of two plots

Clear-cut

77 (1995) 35-51

li

li 0 7 0 5 4 0 0

beech forest

Forest unli

0 1 0 0 10 0 0

(unli)

method

Clear-cut unli

1 0 1 0 9 0 0

(li) and unlimed

ii-

unli 0 21 0 + 2. 0 0

0

0

0

0

0

0

2

0

15 0

2 4

7 0

5 0

3 0

4 +

2 Cl

6 0

LIODIDAE Colenis immunda Sturm Agathidium nigripenne F.

0 0

0 0

1 0

0 1

0 0

0 0

0 +

0 0

SCYDMAENIDAE Neuraphes angulatus Neuraphes sp.

3 0

0 0

1 1

0 1

0 0

+ 0

0 0

0 0

5

7

6

2

14

23

119

22

0 1

0 0

1 1

0 0

0 0

0 0

0 0

0 0

1 6 0

1 4 0

2 14 0

2 9 0

2 0 0

0 0 +

0 0 0

0 0 0

1

5

0

1

0

0

0

0

4

0

0

0

1

0

0

0

0 0 0 1

1 0 0 5

0 0 0 2

0 0 0 1

1 1 + 0

0 0 + +

5 3 0 11

3 0 0 +

CATOPIDAE Nargus wilkini Spence Catops longulus Kelln.

PI’ILIIDAE Acrotrichis

sp.

STAI’HYLINIDAE PROTEININAE Proteinus brachypterus Proteinus oualis Er. OMALIINAE Anthophagus Phyllodrepa Dropephylla

(MU.)

F.

angusticollis Mannh. ioptera (Steph.) gracilicornis Fairm.

OXYTELINAE Coprophilus striatulus STENINAE Stenus latifions

CF.1

Er.

PAEDERINAE Lathrobium fuluipenne (Grav.) Lathrobium brunnipes CF.1 Lathrobium longulum Grav. Domene scabricollis (Er.1

44

A. Theenhaus,

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Ecology

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77 (I 995) 35-51

Table 6 continued Photo-eclectors Clear-cut

Forest

Ii

unli

XANTHOLININAE Xantholinus fricolor (F.) Xantholinus linearis (01.) Othiuspunctulatus (Gze.) Othius myrmecophilus Kiesw.

1 0 1 0

0 0 1 1

STAPHYLININAE Philontus sp. Quedius mesomelinus (Marsh.) Quedius fimatus Steph. Quedius xanthopus Er. Quedius uexans Epph. Quedius maurus (Sahlb.) Quediusfulgidus (F.) Quedius curtipennis Bernh. Quedius sp.

0 1 0 0 0 0 0 0 0

1 1

TACHYPORINAE Mycetoporus brunneus (Marsh.) Bolitobius exoletus Er. Tachinus subterraneus CL.) Tachinw laticollis (Grav.) Tachinus marginellus (F.) Tachyporus chrysomelinus L.

1 0 0 0 1 0

Aleocharinae PSELAPI-IIDAE Bryaxis nodicornis (AubC) Plectophloeus erichsoni (Aubt)

BYBRHIDAE Cytilus sericeus

Ii

li

unli 0 +

0 s 0

0 I 0

0 0

3 0

2 0

0 0 0

1 0 1

0 0 0

0 0 0

0

2

0

0 0 0 0 0 0

0

0

0

0 0 1

0

0 0

9

1s

26

28

0

1 1

0

0 0

0 0

1 0 0 1 1 0

2 0

0

0 0 1 1 0 0

F.

3

2

0

0

11 0

19

larvae

0

0

0

0

0

1 0 0 0

0 0 1

0 0 0 0

0 0

0 0

0 0

0

CF.)

NITIDULIDAE Brachypterus urticae (F.) Thalycra feruida (Olivier) Epuraea longula Er. Epuraea sp.

0

0 1 0 7 0

0 2

1 0 1 0 1

0

0 0

0

method

Clear-cut unli 0 0 2 1

CANTHARIDAE Malthodes mysticus Kiesw. CantharisFgurata Mann. Cantharis obscura L. Bhagonycha lignosa (MU) Podistra rufotestacea (Letzn.) Malthodes sp., females ELATEIUDAE Athous subfkscus Athous subfkscus,

Funnel

Forest Ii

unli

1 0 3 IL!

I 0 b 7

I 0 3 37

0 0 cl 0 0 0 0 0 0

0 0 + 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0

0 + 0 I 0 0

0 0 0 0 0 0

110

78

0 0

0 0

0 0

0 0

0 0

0 0

0 2 0

0 0 0

0 0

2

0

0 0 0 0 0 0

3 8

1 0 0 0

0

0 0 0 117

50

0 0

1 150

+

2 168

0 0 0

3 339

+

0 0 0 0

0

2 485

0

0

1

0

0 0

0 0 0

+

A. Theenhaus,

M. Schaefer/Forest

Ecology

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77 (1995)

4s

35-51

Table 6 continued Photo-eclectors Clear-cut li unli

Funnel method Forest Ii

unli

Clear-cut li unli

Forest Ii

unli

RIIIZOPIIAGIDAE dispar (Payk.) ferrugineus (Payk.)

Rhiwphagus Rhisophagus

CRYPTOPHAGIDAE Atomaria sp. Cryptophagus

silesiacus

2 3

0

1

2

0 0

0 0

0 0

0 0

0 0

2 1

3 0

3 0

2 1

0 0

0 0

2 0

0 0

1 0 8

16 1 3

2 0 4

3 0 0

0 0 0

0 0 0

1 0 0

0 0 0

0 0 1

0 0 0

0 0 0

0 1 0

+ 0 0

0 0 1

+ 0 0

0 0

0 0

0 0

0 0

0 1

0 0

0 0

0 0

0 0

0

0

0

0

0

0

0

0

0

0

1

0

0

0

0

0

0

0

0

0

+

0

0

0

0

1

1

1

0

0

0

0

2 1 1 0 0 0 1 0 0 1 0

0 0 1 0 0 2 1 0 0 0 0

6 0 6 1 1 so 0 0 0 0 1

5 0 14 2 1 70 0 2 0 0 2

0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0

0 0 1 0 0 0 1 0 + 0 2

0 0 + + + 3 0 1 0 0 1

1

0

0

0

0

0

0

0

Ganglb.

LATI-IRIDIIDAE Corticaria sp. Cartoderema elongata (Curt.) Lathridius nodifer Westw.

COCCINELLIDAE Propylaea quatuordecimpunctata Halyzia sedecimguttata (L.) Coccinella septempunctata L.

CL.1

1

PY’I’IUDAE Rhinosimusplanirostris Rabocerus foveolatus

(F.) (Ljungl

MORDELLIDAE Nassipa

rufilabris

(Gyll.)

SCARABAEIDAE Melinopterus

(Brahm)

prodromus

CHRYSOMELIDAE Batophila sp. SCOLYTIDAE Xyloterus

domesticus

(L.)

CURCULIONIDAE Polydrusus undatus (F.) Sitona cambricus Steph. Strophosoma melanogrammum (F&t.) Strophosoma capitatus (Deg.) Otiorhynchus singularis CL.) Phyllobius argentatus (L.) Rhynchaenus fagi (L.) Rhinomias forticornis @oh.) Ceutorhynchus quadridens Germ. Ceutorhynchus erysimi Germ. Acalles camelus (F.)

ASPIDIPIIORIDAE Aspidiphorus

orbiculatus

(Gyll.)

CLAMBIDAE Clambus punctulum Beck 1 0 0 0 0 0 0 Methods: ground photo-eclectors (capture period 11 March to 4 November 1992) and funnel extraction method (mean of four sampling dates 1992). +, between 0 and 1 ind. rn-’ found.

46

A. Theenhaus,

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Ecology

and Management

Rhagionidae, Empididae, DoHybotidae, Pipunculidae, Tachinidae,

3.2.1.4. Zoophages.

400

35-51

Macroceridae and Keratoplatidae form part of the zoophages. Emergence abundance of total zoophagous feeders was comparable for all experimental plots. With Empididae and Dolichopodidae, however, a significant change became evident: the emergence abundance value for Empididae increased after liming (P < 0.05; Table 5). Dolichopodid numbers were significantly higher on the clear-cut plots relative to the beech forest plots (P < 0.01).

By means of artificial trunks, the attraction, which tree trunks exert on the soil macrofauna (Chilopoda, Diplopoda, Coleoptera, Dipteral, was examined by Funke and Herlitzius (1984). These authors observed that Lonchopteridae avoided the artificial trunks. This finding is consistent with the high number of Lonchopteridae found on clear-cut plots.

lichopodidae,

77 (1995)

Ind lm2 a) Lumbricidae

fa Dendiobaena.

~uven~l

f7 Dendrobaena

octaedra

!nd /m2

lnd lm2 ”

::v

c) Curculionidae 4-

HTrechus

q

quadrtstrlatus

Trichocellus

r?lacldus

0 PI oblongopuncratus c]P:

metallicus

lnd /m”

80 I

1) Lithobiidae

fi0

Cl noI1

q Not

Aleochmna

punctulatus

Cl /I

f0 noll

001 mother

f0 I/

myrmecophllus ta L , anamorph

Fig. 4. Density of the soil macrofauna (ind. m -2 ) on limed and unlimed clear-cut Soiling mountains, sampled by funnel extraction method (mean of four sampling limed; fo noli, beech forest, not limed; fo li, beech forest, limed.

q

L muiabik

q

1 curtlpes

bother

plots, and on limed and unlimed beech forest plots in the dates 1992). cl noli, clear-cut, not limed; cl Ii, clear-cut,

A. Theenhaus,

M. Schaefer/Forest

Ecology

3.3. Coleoptera A total of 24 Coleoptera taxa were recorded, with 86 species/groups identified (Table 6). In funnel samples Aleocharinae were most abundant, averaging 89 ind. mV2. They were followed by Acrotrichis spp. (44 ind. rnm2> and Othius myrmecophilus (12 ind. me2). In the catches with the ground photoeclectors Phyllobius argentatus (30 ind. mm2) was most abundant, followed by Aleocharinae (19 ind. mp2) and Athous subfuscus (9 ind. mw2) (Table 6). The average population density of Coleoptera was 175 ind. rnp2 (funnel method) and 224 ind. me2 (ground photo-eclectors) (Fig. 3~). By means of the funnel method, on the clear-cut plots, an average of 130 ind. rnp2 was found, whereas comparatively high average numbers were maintained on the beech forest plots (219 ind. m-2 ). The density of Coleoptera was higher on the limed plots (217 ind. me2) than on the unlimed plots (132 ind. me2 ) (funnel method) (Fig. 3(c)). By means of the ground photo-eclectors, on the clear-cut plots, an average of 92 ind. rnw2 was found and 179 ind. m-‘, on average, on the beech forest plots (Fig. 3(c)). Reasons for these differences are discussed in the following chapters dealing with the dominating families. Perel (1965) found a decrease in the total density of Coleoptera after cutting, whereas Huhta et al. (1967) reported an increase in Coleoptera soon after clear-cutting. 3.3.1. Larvae of Athous subfuscus (Elateridae) On the beech forest plots, the mean abundance of the larvae of Athous subfiscus was 412 ind. rne2, whereas comparatively low numbers were maintained on the clear-cut plots (Fig. 4(b) and Table 6). Correspondingly, the emergence abundance of Athous subfuscus was significantly (P < 0.001) reduced on the clear-cut plots. Funke and Herlitzius (1984) observed that Elateridae were attracted by artificial tree trunks. These observations agree with the decline in Athous subj&us population after clear-cutting. Since the larvae of Athous subfuscus stay in the soil for 3-5 years (Moritz, 1986) and since clear-cutting was performed 3 years ago, a direct influence of the experimental treatments on the larvae of Athous subfuscus must be considered. During the cutting

and Management

77 (1995)

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47

and removing of the trees in autumn 1989, patches of the upper strata of the soil, the preferred habitat of Athous subfuscus larvae (Moritz, 1986), were affected (J. Schauermann, personal communication, i993). During this time, the larvae, which could be expected to hatch in the year of the present study, were already present in the soil. It could be concluded that the decrease in Athous subfuscus after clear-cutting was caused by the death of the larvae due to the experimental treatment. 3.3.2. Curculionidae Eight curculionid species were detected. In the funnel catches Phyllobius argentatus prevailed comprising 32% of the total Curculionidae, followed by Acalles camelus (26%) and Strophosoma melanogrammum (12%). Clear-cutting resulted in a complete breakdown of the curculionid population. On the beech forest plots the average abundance of Curculionidae was 5 ind. rne2. No specimen of Curculionidae was found on the clear-cut plots (Fig. 4(c) and Table 6). This agrees with the results of the eclectors, where the curculionid population was reduced on the clear-cut plots, with a significance level of P < 0.001 (Fig. 3(d)). While comparatively high numbers were maintained on the beech forest plots (80 ind. me2 on average), on the clear-cut plots only 5 ind. me2 emerged on average. The effect of clear-cutting on Polydrusus undatus (P < 0.051, Strophosoma melanogrammum (P < 0.001) and Phyllobius argentatus (P < 0.001) was a significant decrease in emergence abundance. How can the strong decline in Curculionidae on the clear-cut plots be explained? The adults of most of the Curculionidae found in this study feed on leaves in the crowns of beech trees. After they emerge from the soil, the adult beetles either fly into the crowns of the beech trees or they climb up the tree trunks. It makes sense, therefore, that the females choose oviposition sites close to beech trees. Funke and Herlitzius (1984) reported on the attraction of beech trees for the adults of the Curculionidae Polydrusus sp. and Strophosoma sp. 3.3.3. Carabidae Seven species of Carabidae were found. Of these, Trechus quadristriatus, Pterostichus oblongopuncta-

48

A. Theenhaus,

M. Schaefer/Forest

tus, Trichocellus placidus and Pterostichus metallicus were most abundant (Table 6). On the limed plots the average density of Carabidae was higher (20 ind. m-* by the funnel method and 12 ind. mm2 using ground photo-eclectors) than on the unlimed plots (3 and 11 ind. m-‘, respectively) (Fig. 4(d); funnel method only). Similar patterns were observed for the individual species. Of Trechus quadristriatus on the limed plots, an average of 14 and 2 ind. rnm2, respectively, were found, while on the unlimed plots an average of only 1 and < 1 ind. m-‘, respectively, were found. The abundance of Trichocellus placidus was highest on the limed clear-cut plots (an average of 3 and < 1 ind. rnb2, respectively). In the catches with the funnel method, liming had been slightly favourable for Pterostichus oblongopunctatus. Furthermore, clearcutting had a positive effect on the population density of Pterostichus oblongopunctatus. The average density of this species was 3 ind. rn-’ on the clear-cut plots and 1 ind. mm2 on the beech forest plots. No tendency was found for this species in the samples taken with the ground photo-eclectors. Knie (1975) reported that the density and species variety of the carabid fauna in the humid and acidic forests near Bonn (Germany) depend on the amount of vegetation. He found that a low density of the herb layer caused a decline in species numbers and an increase in population density. In clear-cuts, where the herb layer was well developed, Knie detected the highest number of species, but only a small population density. In the present study, however, no obvious change in species numbers was found. Furthermore, the population density was highest on the plots with a dense herb layer (limed plots).

3.3.4. Staphylinidae The average abundance of Staphylinidae was 114 ind. me2 (funnel method) (Fig. 4(e)) and 38 ind. m-2 (ground photo-eclectors) (not shown). In the catches using the funnel method, 78% of the Staphylinidae were Aleocharinae, 14% were Othius myrmecophilus and 3% were Othius punctulatus. In the catches with ground photo-eclectors, 51% of the Staphylinidae were Aleocharinae and 17% Phyllodrepa ioptera. No obvious differences between the treatments were observed in the samples taken with

Ecology

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77 (1995)

35-51

ground photo-eclectors, whereas the funnel method revealed a decline in the population density of Staphylinidae after clear-cutting (P < 0.01) (Fig. 4(e)). The same response was observed in Aleocharinae (P < 0.051. Furthermore, the liming treatment caused an increase in the abundance of Aleocharinae (P < 0.05). Othius punctulatus presented no evident pattern. On the unlimed beech forest plots, the average density of Othius myrmecophilus was five times as high (37 ind. m-*) as on the limed beech forest plots (7 ind. rne2). Clear-cutting had a negative effect on the population of Lathrobium fklvipenne. No individual of this species was detected on the unlimed clear-cut plots. On the limed clear-cut plots, the abundance of this species was relatively low. On the beech forest plots, however, an average of 4 ind. me2 of Lathrobium jklvipenne were collected. For Lathrobium brunnipes similar patterns were observed (Table 61. Huhta et al. (19671 found an increase in Staphylinidae soon after clear-cutting, while Szujecki (1971, 1972) reported a decline in Staphylinidae in clear-cut areas. 3.4. Lithobiidae The average density of Lithobiidae was found to ~JJ lxveemu 31 ind. me2 (unlimed forest plots) and . -2 (limed forest plots) (Table 7). Four species were identified, the predominant one being Lithobius mutabilis, averaging 18 ind. rn--‘. The density of Lithobius curtipes was 15 ind. mm-‘. Just one individual of Lithobius macilentus and one of Lithobius dentatus were found. Table I Population density (ind. mm2 ) of Lithobiws spp. on the limed (Ii) and unlimed (unli) clear-cut and the limed (Ii) and unlimed &mli) beech forest plots in the Solliig motintains (1992/1!B3) Clear-cut

Lithobius curt@ C.L. Koch Lithobius mutabilis L. Koch Lithobius macilentus L. Koch Lithobiusdentutus C.L. Koch Lithobius, juvenile

Forest

-

ii-----

unli

Ii

unli

17 14 0 0 19

10 19 + 0 13

24 28 0 i 28

9 I2 0 0 10

Funnel method (mean of four sampling and 1 ind. me2 found.

dates 1992).

+ , between

0

A. Theenhaus,

M. Schaefer/Forest

Ecology

The average density of all Lithobius spp. was higher on the limed plots (65 ind. m-‘) than on the unlimed plots (37 ind. m-‘1 (P < 0.001) (Fig. 4(f)). The same was true for the anamorphic Lithobiidae, with a significance of P < 0.01. Lithobius curtipes thrived on the limed plots as well. An increase in Lithobius numbers, due to liming, was described by Schauermann (1985). Schaefer (1991~) stated that Centipedes are an important group of the predatory macrofauna in the soil-litter subsystem. Lithobiidae feed mainly on mobile animals such as Collembola, Diptera and Lumbricidae. It may therefore be assumed that the relatively high lumbricid numbers on the limed plots have contributed to the increase in Lithobius. Gretschy (1952) pointed out that Myriopoda need highly porous soil because they lack digging ability. It is possible that the high number of Lumbricidae on the limed plots increases the porosity of the soil, thus improving the microhabitat for the Lithobiidae.

4. General conclusions In this study, the change of soil moisture, caused by the treatments, was assumed to be the most important factor determining the change in population densities. Other factors, such as soil and litter chemical parameters, were not considered because of the speculative nature of the influence of these factors on the abundance of faunal groups. It has been hypothesized that liming changes moder profile into mull profile. Schaefer and Schauermann (1990) compared the soil fauna characteristics of two German beech forests-one on mull soil, the other on moder soil (Soiling). They found that Lumbricidae, Chilopoda and carabid beetles are favoured on mull soil. The results of the present study indicate a positive effect of liming on the abundance of these taxa and, therefore, a change from moder into mull soil. Mull soils are characterized by a much higher total soil-fauna biomass than moder and mor soils (Schaefer, 1991~). This is because mull soils are dominated by Lumbricidae. Schauermann (1986) points out that consumption

and Management

77 (1995)

35-51

49

rates by saprophages are lower in the forest on moder soil (Solling beech forest) than in the beech mull soil, presumably because mean annual biomass of all saprophages is only 5-6 g rnp2 in the Solling forest. In the present study Lumbricidae and other saprophages such as Sciaridae, Scatopsidae and Tipulidae were most abundant on the limed plots. These groups contribute significantly to leaf-litter breakdown by their feeding activities. Altmiiller (1976) pointed out that Diptera are the most important decomposers in the beech forest of the Solling. The author concluded that the decomposition of litter can be attributed mainly to the activity of sciarid and sciophilid larvae. According to Altmiiller (19761, the larvae of the Sciaridae and Mycetophilidae (mainly Sciophilidae) are consuming 13-29% of the annual litter fall. Hovemeyer (in Schaefer, 1982) estimated that larvae of Sciaridae in a German mull forest processed about 8% of the annual input of litter originating from green phytomass. Binns (1981) assumed that macrohumiphagous Sciaridae and Sciophilidae have a positive effect on the development of microflora. Perel et al. (1971) found a stimulating effect of tipulid larvae (as macrohumiphages) on the decomposition process. Summing up, the results of the present study suggest a change of moder soil into mull soil after liming. Heterotrophic effects are greatest in decomposer processes. In a forest ecosystem about 90-95% of total heterotrophic respiration is contributed by decomposers. Furthermore, the heterotrophic community performs an important function in controlling the fluctuations in the rate of nitrogen release (Schaefer, 1991b). Therefore, because of the increased density of Lumbricidae, Sciaridae, Scatopsidae and Tipulidae on the limed plots, a more rapid mineralization and mobilization of nutrients was expected. This, however, was not found. Instead, on the limed plots (19911, less nitrogen was mineralized compared to the unlimed plots. It has further been hypothesized that the decomposer community decreases as a result of clear-cutting. This, however, has not been found. Lumbricids were not significantly influenced by clear-cutting. This was also true for the macrohumiphagous Diptera. The emergence abundance of Limoniidae on the clear-cut plots was found to be even significantly higher than on the forest plots.

50

A. Theenhaus,

M. Schaefer/Forest

Acknowledgements We thank Dr. J. Schauermann for helpful assistance and many fruitful discussions. For advice on statistical matters we are indebted to Dr. Michael Judas. The study was supported by the Bundesministerium fir Forschung und Technologie. References Altmiiller, R., 1976. Zum Energieumsatz von Dipterenpopulationen im Buchenwald (Luzulo-Fagetum). Thesis, Glittingen. Altmiiller, R., 1979. Untersuchungen liber den Energieumsatz von Dipterenpopulationen im Buchenwald (Luzulo-Fagetum). Pedobiologia, 19: 245-278. Bauhus, J., 1994. Stoffumsatze in Lochhieben. Berichte des Forschungszentrums Waldlikosysteme, A 113. Thesis, Gdttingen. Bauhus, J. and Barthel, R., 1994. Mechanisms for carbon and nutrient release and retention in beech forest gaps. II. The role of soil microbial biomass. Plant Soil, 37: 17-24. Bauhus, J. and Bartsch, N., 1995. Mechanisms for carbon and nutrient release and retention in beech forest gaps. I. Microclimate, water balance and seepage water chemistry. Plant Soil, 168-169: 579-584. 1981. Fungus gnats (Diptera: Mycetophilidae/ Binns, ES., Sciaridae) and the role of mycetophagy in soil: a review. Rev. Ecol. Biol. Sol., 18: 77-90. Brauns, A. (Editor), 1954. Terricole Dipterenlarven. Giittingen, Musterschmidt, 179 pp. Cramer, E., 1968. Die Tipuliden des Naturschutzparkes Hoher Vogelsberg. Dtsch. Entomol. Z., N.F. 15(1/3): 133-231. Ellenberg, H. (Editor), 1971. Integrated experimental ecology. Methods and results of ecosystem research in the German Soiling project. Ecol. Stud., 2: 1-214. Ellenberg, H., Mayer, R. and Schauermann, J. (Editors), 1986. Gkosystemforschung, Ergebnisse des Sollingprojektes. Ulmer, Stuttgart, 507 pp. Feldmann, R., 1992. Die Bodenmakrofauna im Lennebergwald. 1. Die Dipteren. Mainz. Naturwiss. Arch., 30: 171-241. Funke, W., 1971. Food and energy turnover of leafeating insects and their influence on primary production. Ecol. Stud., 2: 81-93. Funke, W., 1991. Tiergesellschaften in Waldern. Kernforschungszentrum, Karlsruhe. Funke, W. and Herlitzius, H., 1984. Zur Orientierung von Arthropoden der BodenoberfHche nach Stammsilhouetten im Wald. Jahresber. Naturwiss. Ber. Wuppertal, 37: 8-13. Gretschy, G., 1952. Die Sukzession der Bodentiere auf Fichtenschllgen. Veroeff. Bundesanst. Alp. Landwirtsch. Admont, 6: 25-85. Healey, I.N. and Russel-Smith, A., 1971. Abundance and feeding preference of tly larvae in two woodland soils. 4. Colloq. Pedobiol. Dijon, 1970. Ann. Zool. Ecol. Anim. Numdro horsserie, Paris 3: 177-191.

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